Washington police investigator George Klein Jr. examines bullet strikes in one of the doors of the US Holocaust Memorial Museum in Washington, Thursday, a day after a shooting left a security officer dead and the gunman wounded.

James Von Brunn, the Holocaust Museum attacker alleged to have killed a security guard, was a former PT boat captain who had argued he fought for the wrong side in World War II; Joshua Cartwright, who killed two Florida sheriff's deputies earlier this year in part because of his frustration over the election of a black president, was a National Guardsman; and Richard Poplawksi, who spent a short time in the Marine Corps, killed three Pittsburgh police officers in April. He had been a regular contributor to white supremacist web sites.

A 2008 FBI counter-terrorism report said that 203 veterans had joined white supremacist groups in the last decade, 19 of whom had served in Iraq or Afghanistan.

What's more, the Department of Homeland Security report ("Right-wing Extremism: Current Economic and Political Climate Fueling Resurgence in Radicalization and Recruitment") warned that, though only a small number of military veterans join such groups, they often occupy new leadership positions in a white nationalist movement that had largely been defanged since its high point in the 1990s.

"Looking ahead ... the military training veterans bring to the movement and their potential to pass this training on to others can increase the ability of lone offenders to carry out violence from the movement's fringes," the report noted.

At the time of the DHS report's release, conservative politicians, media commentators, and veterans groups lambasted the report, calling it an insult to American veterans. DHS Secretary Janet Napolitano retracted the report, acknowledging poor wording in tying radical right-wing groups to the trend.

But as an internal law enforcement tool, the report hit the right notes, some veteran groups say today.

"We felt the report read in full accurately described the threat or susceptibility of returning vets to be recruited by any extremist group," says Ray Kelley, legislative director of AMVETS.

"I think a lot of Americans got removed from that intent and pulled into the political mention of right-wing groups," says Mr. Kelley. "But it's not that. It identified a susceptibility ... that young vets, when they came back, are disenfranchised because they are twice as likely to be unemployed as their civilian counterparts and they have stress issues that all too often go untreated."

Some of the recruitment has even been in the open. The National Alliance, a white separatist group, once bought a billboard outside a North Carolina Army base, urging veterans to join.

Former FBI agent Todd Letcher, who led the Eric Rudolph investigation, says the threat of "lone wolf" extremists with military backgrounds may be greater than the spectre of veterans leading a resurging white nationalist movement. [Editor's note:The original version misspelled Mr. Letcher's surname.]

"When you're talking about lone wolves, they're not joiners and they're not going to be part of a group, even if you try to recruit them," says Mr. Letcher. But he adds: "Training with respect to firearms, evasion and hiding tactics, all that is taught in the military. And is that something that's helpful for a particular cause, for a lone wolf or a group? Yes, it is."

"The DHS was spot on," says former Marine T.J. Leyden, author of "Skinhead Confessions." "There’s guys who may have had three tours over there and they’re now coming back to a country where the economic outlook isn’t very bright. Plus, you’ve been over there fighting for your country and now you can’t get a job because we won’t stop illegal immigration, and they’ll bail out the Jews but not the hardworking man in Detroit. Some of these kids are going to eat that up."